# Task Cancel Assurance

> Task Cancel Assurance is a paid API for AI agents from phion.systems, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-23).

Verifies the cancellation state of an agent task and identifies any unresolved side effects left behind

## Facts

- Endpoint: POST https://phion.systems/v1/paid/trust/task-cancel-assurance?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-23
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/task-cancel-assurance-d25e136b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_fx-O9yckkUklL5xq9xCuC

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability task-cancel-assurance-d25e136b -d '<json body>'
```

Example prompt: Can you verify that the task I just cancelled is fully resolved — confirm its cancellation state and flag any unresolved side effects it may have left behind?

## When to prefer this

Use this endpoint when an AI agent or orchestrator needs independent, signed assurance that a task cancellation was complete and did not leave behind unresolved side effects — particularly in multi-agent pipelines, paid workflows, or any scenario where partial execution could cause downstream harm, double-spending, or orphaned state. Prefer this over internal checks when third-party verification or a portable signed receipt is required for auditability.

## Known failure modes

- Task ID not found or unrecognized, returning an error with no state information
- Task has not yet been formally cancelled, so cancellation state cannot be confirmed
- Insufficient information provided to identify the task, resulting in a validation failure
- Service temporarily unavailable, returning a 5xx error with no receipt
- Side effect resolution status cannot be determined due to missing upstream records

## How this service works

Verify cancellation state and unresolved side effects

## Output

A structured receipt confirming the cancellation state of the specified task, listing any unresolved side effects detected, and providing a signed assurance that the verification was independently performed — allowing downstream agents or orchestrators to safely proceed or take remediation steps.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input",
  "output"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "body"
   ],
   "properties": {
    "body": {
     "type": "object",
     "additionalProperties": true
    }
   }
  },
  "output": {
   "type": "object",
   "required": [
    "example"
   ],
   "properties": {
    "example": {
     "type": "object",
     "additionalProperties": true
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json"
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/task-cancel-assurance-d25e136b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from phion.systems](https://www.zero.xyz/host/phion.systems/llms.txt)